1. Field of the Invention
The present invention generally relates to an access method, an information recording and reproducing apparatus, and a recording medium, and particularly relates to an access method, an information recording and reproducing apparatus, and a recording medium capable of recording and reproducing information into and from an optical disk when switching from an operation of recording information into an optical disk to an operation of reproducing information from the optical disk or switching from an operation of reproducing to an operation of recording.
2. Description of the Related Art
In recent years, recording video data into optical disks, such as DVDs (digital versatile discs), has become common due to improvements in digital techniques and data compression techniques. Examples of commercially available apparatuses for recording video data into optical disks include optical disk devices used with personal computers, and DVD recorders, which are suitable especially for recording contents provided via cable and satellite as video data. In these apparatuses, optical disks are rotated by spindle motors.
If such an apparatus has a time shift function, the apparatus can reproduce content from the beginning even when the content is still being recorded into an optical disk (see, for example, Patent Document 1). For doing so, recording and reproduction are alternately performed. In this type of apparatus, an optical pickup device seeks a reproduction position separate from a recording position when switching from recording to reproduction, and seeks a recording position separate from a reproduction position when switching from reproduction to recording.
Generally, so-called CLV (Constant Linear Velocity) mode, in which a spindle motor is controlled so as to make the linear velocity constant, is used when video data are recorded into an optical disk, whereas so-called CAV (Constant Angular Velocity) mode, in which the spindle motor is controlled so as to make the angular speed constant, is used when the video data recorded in the optical disk are reproduced.
In some cases, the rotating speed of the spindle motor for recording is different from the rotating speed for reproduction, and therefore the rotating speed of the spindle motor is changed when switching between recording and reproduction.
That is, when the time shift function is activated, a seeking operation of the optical pickup device and a changing operation of the rotating speed of the spindle motor are repeatedly performed. In order to perform recording and reproduction smoothly, it is desirable to shorten time required for the seeking operation and time required to change the rotating speed.
An apparatus disclosed in Patent Document 1 is configured such that the rotating speed of a spindle motor for reproduction is equal to the rotating speed for recording, and therefore does not need to change the rotating speed of the spindle motor when switching between recording and reproduction. In some cases, however, reproduction conditions are not suitable, so that image quality might be reduced.
[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-15823